1. Which is longest river in world ?

Answer: Nile, Africa

2. Which is longest railway station ?

Answer: Grand Central Terminal, Chicago(USA).

3. Which is the state largest by area in India ?

Answer: Rajasthan

4. Which is Longest national highway of India ?

Answer: NH-7 ( Varanasi to Kanyakumari - 2,369 km)

5. Which is the lightest gas ?

Answer: Hydrogen

6. Which Indian state is having longest coastline ?

Answer: Gujrat

7. Which is highest dam in world ?

Answer:

Jinping-I Dam - 305 m (1,001 ft) in China on Yalong river.
Second Highest is Nurek Dam 300 m (980 ft) Tajikistan on Vakhsh river.